1. Field
The present disclosure relates to motor vehicles, and more particularly to improved functionality and integration in windshield wiping methods, apparatus and design for manufacturability.
2. Description of the Related Art
For the many advances in automotive technology, there have been surprisingly few advances assuring visibility during precipitation driven by truly inclement weather. That is, since the invention of windshield wipers in 1903, over a century has passed without a solution that can provide users with adequate clearing of heavy rain, ice or snow. In order to provide some context, aspects of a prior art windshield wiper are introduced.
Referring to FIG. 5, there is shown a prior art windshield wiper 51. The prior art windshield wiper 51 includes a blade, or squeegee, 52. The blade 52 is generally fabricated from rubber, a soft polymer or other similar material that provides for a “squeegee” action, that is, an action that sipes water away from an exterior surface of a windshield (i.e., expels water from the surface). The blade 52 is attached to a spine 53. The spine 53 provides a rigidity required to ensure downward pressure which is delivered through an arm 57 and upon the blade 52 is effectively communicated along a length, L, of the prior art windshield wiper 51. In common embodiments of the prior art windshield wiper 51, the pressure is evenly distributed through a suspension system that includes components such as at least one primary armature 54 and often a secondary armature 55. As is commonly recognized, the secondary armature 55 often includes a single coupling 56 for coupling of the prior art windshield wiper 51 to the arm 57. The arm 57 is driven by a motor and mechanical assembly (not shown) which provides for repetitive travel of the prior art windshield wiper 51 across a viewing area of the windshield. More recently, flat beam-blades have been implemented based on press-fit leaf spring blades inserted in longitudinal grooves above the squeegee.
Present day windshield wipers 51 are generally useful in limited to light rain and often are inadequate to handle a large volume of rain, such as during intense downpours. In intense rainstorms, wiper blades are unable to displace the high volumes of water. Generally, the wipers smear the rain into blurring sheets and create very limited visibility through the windshield. Increasing the speed of the traverse of the wiper has been useful, but this also causes limitations in visibility. Further, high speeds can cause excessive wear to a wiper system. These problems have been persistent in the auto industry for over a century. Other problems with present day windshield wipers 51 are known.
For example, while windshield defrosters can help in freezing weather, present day internal, in-cab, heated and fan blown air windshield defrosters are manifestly ineffective in melting ice deposited on surfaces of the prior art windshield wiper 51. Any one that has driven in icing weather recognizes that the glass windshield is a poor thermal conductor for heat transfer to the squeegee blade of the typical windshield wiper. At low ambient temperatures, ice forming on the various parts of the prior art windshield wiper 51 results in dangerously poor visibility for automobile, bus and truck drivers alike.
Various attempts have been made to address icing on wiper blades. Among these are designs that conduct heat to the wiper blade 52. However, efforts involving conduction heating are inefficient and generally ineffective. That is, as silicone rubbers and synthetic polymer equivalents used in wiper squeegees are good thermal insulators, the designs fail to perform as intended.
The prior art has been unable to solve the problems associated with the thermal insulator property of flexible rubber or polymer windshield wiper blades. The thermodynamics of heat transfer are poorly realized in prior art implementations which teach embedding wires into channels opened into the thermally insulating wiper blade body. Considering the radiation emission pattern of a wire to be that of a cylindrical isotropic radiator, the majority of the heat energy is lost into directions not effective for melting ice on the blade-edge and sidewalls.
Some other efforts have addressed the thermal conductivity limitation by additions of carbon-based materials such as carbon-fibers or graphite or nanoparticle admixtures in the materials used in the blade 52. These solutions enhance thermal conductivity with an attendant increase in the cost of materials. Notably all polymer and rubber materials suffer diminished lifetimes resulting from conductive thermal cycling associated with heating and cooling of the blade.
Likewise, embedding resistive wires into the wiper blades (i.e., heating a thermal insulator) reflects an attempt to overcome the fundamental physics involved. For the same reason, conduction heating of insulators is inappropriate. Heated windshield fluids distributed through capillary tubes have been reported to have caused fires or burn injuries.
With the millions of drivers on the road today, and the frequent presentment of rain and snow hazards, an improved windshield wiper is of great need. The improvements should be cost effective, and be equipped to limit the impact of precipitation for the variety of inclement conditions that confront drivers around the world.